Design and fabrication of piezoelectric coupled MEMS resonators

Multilayer MEMS resonators with physical constraints (coupling beams) were designed, fabricated and characterized, including cantilevers and clamped-clamped beams. This project focused on how the resonance frequencies and coupling constant depend on the geometry of the coupled clamped-clamped beams. The process flow with three masks was used and modified to successfully fabricate the devices. The XRD results show a good quality aluminum nitride active layer. Digital Holographic Microscopy was used to find the in-phase and anti-phase resonance frequencies of the devices. The coupling constant was calculated and compared with FEM simulations by Comsol. The trends follow well with the simulations and analytical theory. However, some unexpected correlations show up of the resonance frequencies and coupling constant of clamped-clamped beams with variable width and gap, which should be further investigated. The general geometry was proposed for coupled devices working as high-sensitivity sensors.